Circuit breaker



Oct. 20, 1953 H. s. GANO ETAL CIRCUIT BREAKER Original Filed May 7, 1945 sup v INVENTORS f/ar/an 6. Game and Gard/d1 geese 3/ 7 ATTORN Patented Oct. 20, 1953 cmoorr BREAKER HarlanS; Gano and Gerald Freese, Beaver,

Pa., assignorsto Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Originalapplication May 7, 1945, Serial No.

592,446,. now Patent No. 2,624,815, dated-January 16, 1953.

Divided and this application March. 19,1952, Serial No. 277,416

14' Claims;

This invention relates to' circuit interrupters, and more particularly to manually "and automatically operable circuit breakers for Controlling lighting and other small or moderate power electric circuits.

This application is a division ofour copending application Serial No. 592,446, filed May '7', 1945, now Patent No; 2,624,815 dated January An object of the invention is to provide an improved circuit breaker. having few'parts, which is compact, accurate and reliable in operation and inexpensive to manufacture.

Another. object of. the invention is to provide a circuit breaker embodying an improved thermally and magnetically responsive trip device wherein adjustment of thethermal trip does not affect the instantaneous trip characteristic.

Another object of the. invention is to provide a simplified construction in which the currentcarrying bimetallic trip memberenergizes a trip magnet mounted independently. of the bimetallic member with. the bimetallic member moved by the magnetto trip the breaker.

A further object of theinventionis to provide a sensitive magnetic. trip by having, a small air gap which can be energized by current flow in a bimetal acting as a singleetur'n. coil with the bimetal being moved" magnetically to. trip the breaker, and at the sametime to make it' possible for the bimetal to move. freev of the. magnetic structure and not be impedediinits bending due to heating which could cause it to take a permanent set and lose its. calibration.

Another object of the inventioniat'o. provide a circuit breaker in which the parts of. thebreaker are assembled at low cost bybeing laid in; re.- cesses in. a two-part, housing of insulating. mate.- rial without the use of any frame other than the. housing.

The novel features. that are considered characteristic of the. invention are set. forthin particular in the appended claims. The invention itself, both as to structure and. operation, to.- gether with additional objects and. advantages thereof;.will be best understoodfrom the follow ing detailed description of several embodiments thereof when read in conjunction with the. accompanying drawing, in which;

Figure 1 is a side elevational view partly in section, of a circuit'breaker embodyingthe'principles of the invention, the, cover plate having been removed more clearly to illustrate invention, the breaker mechanism'beingshown' in the closed-circuit position;

2. Fig. 2 is a side elevational view of thecircuit breaker similar to Fig; 1, showing the breaker mechanism parts in the tripped-open position; Fig. 3 is a transverse sectional View of the circuit breaker taken substantially along line IIIIII of Fig. 1 and looking in the direction of the arrows; I

Fig. 4 is a fragmentary sectional view taken substantially along the'line ofFig. 1" and looking; in the direction of the arrows. 7

Referring to Fig. 1' of the drawing,the cir cuit breaker comprises a housing fl and; a; cover plate t3, both of molded insulating material a stationary contact I5, a cooperatingmovablejcontact l1, an operating mechanism indicated generally' at [9, and a trip device indicated generallyat '21, The housing ll and the cover l3 serve as a frame for the breaker and are molded to provide various recesses, and surfaces. for" removably receiving and supporting all of the parts'i of the breaker. The parts are inserted through the open side of. the housing. l'l when the cover l3j is removed and are retainedin mountedi position in the proper relation to each other when the cover is assembled on the housing an df secured thereto. The stationary" contact L5 is rigidly secured to the inner endof; a terminal 23- dis posed in an angular'tr'a'nsverse slot 25; in the housing. The. terminal. 23 extendsoutside the housing and has apscrew Z'l threaded into. an opening in the terminal to providemea'ns whereby this terminalmay be connected" in an electrical. circuit. v

At the end of the breaker opposite. the't'ermijnal 23 is a terminal 29' havinga screw 31 threaded into an opening therein for connectingv this. terminal in anv electrical circuit. The terminal 25 extends through an opening inthe housing into the interior of the housin'g where it is bent at right angles and serves to support thetrip device 2.! to be described. later. 7 V

The operating, mechanism comprises a releasable member 33,,amanually operable operating lever or handle 3'5. of molded insulating material, a U-shaped switch arm 31. for. supportingthe movable contact IT and an overcenter. spring 39 connected under tension between the switcharm 3? and the releasable member33i The releasable trip member 33 is pivotally'm'ounted ona fixed pivotpin ii-l supported in an opening in the housing H and in a corresponding opening in the cover I3 and is spaced from the housing and cover by means of spacers 433 The releas able trip member 33 normally releasably restrained in the operating position by the en 3 gagement of the free end thereof with a bimetal element 45 rigidly secured to the upper end of the conductor 29 and forming a part of the trip device 2| which will be described later.

The insulated operating lever 35 is pivotally mounted on trunnions 41 molded integral therewith which are supported in suitable openings in the housing H and cover plate l3. The operating lever has a handle 48 molded integral therewith which projects through an opening 51 in the housing 3 whereby the mechanism may be manually operated to open and close the contacts. A semi-cylindrical portion 53 of the operating lever substantially closes the opening 5? in all positions of the operating lever. The inner portion of the operating lever 35 is bifurcated and the two legs 55 thereof are provided with V- shaped recesses for receiving and supporting the legs 51 of the U-shaped switch arm 3'! which legs are at all times biased into said recesses by the spring 39. Thus, the insulating material of the legs 55 of the handle member directly supports the movable contact or switch member 3? for pivotal movement in opening and closing the circuit. The fact that the inner end of handle member 35 and the switch arm 3'5 are both U- shaped provides a balanced construction and permits the trip member to be a single fiat piece movable between the legs of the two U-shaped members. This construction also permits the use of a single spring centered in the mechanism and used for supplying contact pressure, for actuating the contacts open and closed with a snap action independently of the speed of movement of the operating handle, and for biasing the trip memher and moving the contacts open upon the occurrence of an overload.

The switch arm 31 is connected by means of a flexible connection 53 to the free end of the bimetal element 45, thus completing the electrical circuit through the breaker which circuit extends from the terminal 23 through the stationary and movable contacts !5ll, switch arm 31, flexible connection 59, the bimetal element 45 and the conductor 29.

The circuit breaker may be manually operated to open and close the contacts by operation of the insulating handle 49. Movement of the handle and the operating lever 35 clockwise from the full-line position (Fig. 1) to the position in which it is shown in dotand-dash lines carries the upper end of the switch arm 3! to the left of the line of action of the spring 39 whereupon the spring acts to move the switch arm 3. with a snap action to the open position, shown in dot-and-dash lines in Fig. l. The opening movement of the switch arm is arrested by a projection 61 molded integral with the housing I l which acts as a limit stop for the switch member. Movement of the operating handle 49 and the operating lever 35 in acounterclockwise direction from the dot-and-dash position (Fig. 1) to the full line position moves the upper end of the switch arms 31 to the right of the line of action of the spring 39 which thereupon act to move the switch member to the closed position with a snap action. Movement of the handle 49 in either direction is limited by the member 35 striking the housing H at either side of the pivot 41.

In addition to the bimetal element 45, the trip device 2| also includes an electromagnet comprising a U-shaped core member 53, rigidly secured by means of a screw 35 to the conductor 29 and to the housing ll, and a movable armature 67. The bimetal element 45 from its point of attachment with the conductor 23 is formed inwardly away from the conductor and then extends downwardly substantially parallel therewith between the two legs of the U-shaped magnet core 63. The free end of the bimetal has a latch element 69 thereon which engages and releasably restrains the member 33 under normal circuit conditions. The round head of an adjusting screw 7| which threadedly engages in an opening in the conductor 29 at a point near its upper end, bears against a concave surface in the housing l. An opening 13 through the casing provides for the insertion of an instrument to rotate the screw 7 l. Rotating the screw bends the conductor 29 and moves the bimetal element 45 relative to the member 33 to adjust the latch overlap to thereby vary the time delay tripping point of the breaker without affecting the magnetic air gap or changing the instantaneous tripping characteristic of the breaker.

Upon the occurrence of an overload current below a predetermined value the bimetal element 45 becomes heated, and when heated a predetermined amount, deflects in a direction to release the member 33. When the member 33 is released, the spring 39 acts to rotate it clockwise about its pivot 4| until it is arrested by striking the projection 5!. During this movement the line of action of the spring 35 moves to the right of the pivot of the switch arm 31 whereupon the spring biases the switch arm in opening direction and moves it so that the line of action of the force exerted by it on operating lever 35 shifts across the pivot 41, and actuates both the switch arm 31 and the operating lever to the tripped position in which these parts appear in Fig. 2. The movements of the releasable member 33 and of the switch arm 3'! are arrested by the projection 61 in order to provide an indication that the breaker has been automatically tripped open. The movement of the handle in opening direction on automatic opening operations is stopped in an intermediate position (Fig. 2) by striking a stop pin 1'! projecting from the releasable member 33. The parts are shown in the tripped open position in Fig. 2. It is to be noted from Figs. 1 and 2 that the operating lever 35 is substantially in engagement with the projection T! on the releasable member 33 in both the off and tripped posi tions, but is at a distance therefrom in the on position, so that holding the handle in on position cannot prevent movement of the member 33 and tripping movement of the breaker to open the contacts. This makes the breaker trip free of the handle which means that the contacts will open upon the occurrence of an overload irrespective of the position in which the handle may be held. Positive separation of the contacts is insured by the provision of a projection 8| on the releasable member or carrier 33 which projection, upon release of the carrier, strikes the switch arm 3'! at a point intermediate the ends thereof and starts the switch arm in opening direction.

Before the contacts may be closed following an automatic opening operation, it is necessary to reset and relatch the mechanism. This is accomplished by moving the operating lever 35 clockwise from the tripped position (Fig. 2) slightly beyond the full open position in which it is shown by dot-and-dash lines in Fig. 1. This movement of the operating lever, due to the engagement thereof with the pin 1'! moves the member 33 counterclockwise to reengage the free end thereof with the latch element 69 of the bimetal 45. The contacts may now be closed in -flioz.-prevloimlydescribed manner by movement handle counterclockwise to-the closed position The; OiICUitIbIEB-kfil': is tripped automatically/by theelcctromagnet163-r-61 I in; responsetdoverload CHBIQIIIS- above "the; predetermined. valum. The anmiiuree H of the; electmmagnetis; mourned to a ainst-one: leg; oaths" core-:momher 'flfieand isi mtrain'em' 1m ratractetb position. by means: of a one end immovably mounted berm thc:-core:=member and the; side: wall of the housing-I I32. Theothen endiof-sthe spring 15 througheamopening insthe armatureror supporting-the; armature: and biasing; said armantureztmunattractedipositioni Whom an: overload; above a. predetermined value off-. for instance-m0ll%.- I of; normal: rated current, or a: short circuityoccurs, the. core? member 63 is; energized and immediately attracts thearma'a turerfijl thereto. Theyarmature; Bil? is provided witlrani insulating; button "i=9 i which, ,uporr operati'omof, the: armature, engages. and deflects; the bimetal element dia suflicient distance tastiest the release of; the"- releasable. member 33; and

opening; at the contacts inxthe. .previously' described manner. The breaker mechanismdsreset and tho contactsrclosed following:aminstantana 0.11s tripping operation-1inrtherpreviouslyz described manner.

While the-inventionhaslbeen disclosed inaccordance: withthe provisions. oftbe patent statutes,. it is to be understood-that. various changes in thestructural details, thereofv may be made without-departing from'someof the essential fea.- tunes oft-the. invention. It is desired, therefore, that. thelanguage, of the appended,- claimsv be given. the. broadest reasonable interpretationper.- missible. in. the light, of. the: prior art.

We: claimi as. our: invention; I v

1;. In a circuit-breaker, relatively movable $0.01}:- tarits,v releasable. means. for. effecting. automatic opening. of. said contacts, a thermal-15p responsive member. electrically' connected in seri'eswith said contacts. and. heated in, response to. the. current of. thecircuit of. the 'breaker, said, thermally, responsive. member. flexing.v when heated; aapredeterminediamounuina direction to effect-release of. said. releasable means, and. electromagnetic means, comprising. U.shaped core. member emibracing said. thermally: responsive member, sa-id thermally responsive memberacting, as an energizing. means for said core. member, and. a movable armature pivotallyl supported-on! one, leg. of said Ll-shaped; member,, saidarmature being. op.-

erable by said: cores-member inresponse; toover- I load currents: of predetermined value and. having. a. portionv thereon engageable, With.- said. thermally, responsive. member to. deflect: it and. effect release of, said. releasable. means.

2.. In. aicircuit. breaker, relatively movablecontacts, releasable. means. for effecting, automatic opening of" said. contacts. trip means? normally restraining said releasable'means. and o'peral'ale in response to overload currents to. release, said/re.-

leas'abl'e means, said trip meanscbmprising a. core release. said releasable means,; and saidrtherma'l element deflecting in: the same; direction heated a predetermined amount in response to overload currents below saidpredetermined' and. being. movablefindependeniily of said; arms-- tureto. release-said releasable meanse'aftr: a time delay;

In a circuitrbreaker, relativelymovable' cemtacts, releasable means for effecting: automatic opening of I said contacts a" trip" device normally restraining said releasable: means-Iand operable in IGS'IJOIISBFtO overloadscurrents to releasetsaid releasable means; said trip device including: a bimetallic: element. mounted at one end'and having the other:end'free'tomove; ana'ctuatingfportion; rigid with said. bimetallic element for'movement therewith at all? times and, operable to cause release of. said releasable means; conducttors connecting said-bimetallicelement in circuit with said contacts toecau'se'; heating and bending of thebimetallioelement,a' pair of m'agnetic: members positioned: on opposite sldesf'of said: bimetallic element, one' of said magnetic members being movablymounted and biasedrby springv other than: said bimetallic elementtoi a position away' from the other magnetic:- mama'- ber; said spring beingwmounted" independently of the bimetallic element. and exerting: a constant force on the movable magnetic member irrespective of the movement or thebimetallic element, said movable magnetic: member being movable magnetically against its biasmgvspring in the same direction as said bimetallic element moves when heated and" causing, movement; of the bimetallic element to: move its actuating portion and cause: release of said releasable means, and saidpbi-m'etallic element being mova-v ble independently of: said: movable magnetic member after said; releasable means has been released.

4. In a.- circuit breaker,-. relatively movable contacts; releasable means for: effecting auto:- matic opening of said contacts',, a trip: device normally restrainingsaid: releasable means and operable in response: to overload-f currents to release: said releasablemeans; said trip device in"- cluding; a bimetallic element mounted 'atone end and having the-other end: freatomove, an actuatingv portion rigid withvsaid bimetallic ele ment for; movementtherewith: at all tlmessand operable" to 'causerelease of: said releasable means; conductors connecting; said bimetallic element; in; circuit with said: contacts tocause heating and. bending of the.- bimetallic element, a pair ofmagnetic members positioned on cope-'- site: sidesof. said: bimetallic element, one". of said magnetic members being; movably" mounted. and being. movable magnetically in' the same direce tiom as said: bimetallic element moves when. heated and causing; movement-- of: thebimetallic element: to. move: its actuating; portion; and cause release: ofsai'd releasable means; and; said bimetallic; element being movable independently.- of said movable magnetic member beyond the; po:-- sition. where: the said movable magnetic member engages thesother magneticmember;

5. In a circuit breaker; relatively m'ovable'contil'OtS-g, mleasabl'e: means; for effecting. automatic op ening;v of said. contacts; a. trip i devicev normally restraining. said releasable.- means and! operable in; response. tooverload: currentstd release said releasable. means,. said trip.- device.v including. a bimetallic, element. mounted. at onelend. and havingtlieother end free to. movaahactuatingpoiztion rigid'with said bimetallieelementliormovement therewith at all times and operable to cause release of said releasable means, conductors connecting said bimetallic element in circuit with said contacts to cause heating and bending of the bimetallic element, a pair of magnetic members positioned on opposite sides of said bimetallic element, one of said magnetic members being of U-shape and being fixedly mounted, the other of said magnetic members being movably mounted and being movable magnetically in the same direction as said bimetallic element moves when heated and causing movement of the bimetallic element to move its actuating portion and cause release of said releasable means, and said bimetallic element being movable between the legs of the U-shaped magnetic member independently of said movable magnetic member beyond the position where the said movable magnetic member engages the U- shaped magnetic member.

6. In a circuit breaker, relatively movable contacts, releasable means for eiTecting auto matic opening of said contacts, a thermally responsive member electrically connected in series with said contacts and heated in response to the current of the circuit of the breaker, said thermally responsive member flexing when heated a predetermined amount in a direction to effect release of said releasable means, and electromagnetic means comprising a U-shaped core member embracing said thermally responsive member, said thermally responsive member acting as an energizing means for said core member, and a movable armature pivotally supported on one leg of said U-shaped member and being unattached to said thermally responsive member, said armature being operable by said core member in response to overload currents of predetermined value to engage and deflect said thermally responsive member to effect release of said releasable means, and said thermally responsive member being free of said armature to continue to deflect when heated after said armature has engaged the core member.

7. In a circuit breaker, relatively movable contacts, releasable means for effecting automatic opening of said contacts, a thermally responsive member electrically connected in series with said contacts and heated in response to the current of the circuit of the breaker, said thermally responsive member flexing when heated a predetermined amount in a direction to effect release of said releasable means, and electromagnetic means comprising a U-shaped core member embracing said thermally responsive member, said thermally responsive member acting as an energizing means for said core member, and a movable armature pivotally supported on one leg of said U-shaped core member, said armature being operable by said core member in response to overload currents of predetermined value to engage and deflect said thermally responsive member to effect release of said releasable means, and both said armature and said core member being mounted in the breaker independently of any movable part of said thermally responsive member.

8. In a circuit breaker, relatively movable contacts, releasable means for efiecting automatic opening of said contacts, a trip device normally restraining said releasable means and operable in response to overload currents to release said releasable means, said trip device including a bimetallic element mounted at one end and having the other end free to move, an actuating portion rigid with said bimetallic element for movement therewith at all times and operable to cause release of said releasable means, conductors connecting said bimetallic element in circuit with said contacts to cause heating and bending of the bimetallic element, a pair of magnetic members positioned on opposite sides of said bimetallic element, one of said magnetic members being a U-shaped core member mounted in the breaker on the low-expansion side of the bimetallic element and the other magnetic member being a movable armature positioned at the high-expansion side of the bimetallic element and pivotally supported adjacent one end on one end of the U-shaped core member, said armature having its other end movable toward the other end of the U-shaped core member and having a portion which engages the bimetallic element to bend it in the same direction as it bends when heated and thereby causes the actuating portion rigid with the bimetallic element to effect release of said releasable means, and said bimetallic element being free of said armature to continue moving when heated after the movable end of the armature has engaged the end of the U-shaped core member.

9. In a circuit breaker, relatively movable contacts, releasable means for effecting automatic opening of said contacts, a trip device normally restraining said releasable means and operable in response to overload currents to release said releasable means, said trip device including a bimetallic element mounted at one end and having the other end free to move, an actuating portion rigid with said bimetallic element for movement therewith at all times and operable to cause release of said releasable means, conductors connecting said bimetallic element in circuit with said contacts to cause heating and bending of the bimetallic element, a pair of magnetic mem bers positioned on opposite sides of said bimetallic element, both of said magnetic members being mounted in the breaker independently of any movable part of the bimetallic element, one of said magnetic members being a U-shaped core member mounted in the breaker on the low-expansion side of the bimetallic element and the other magnetic member being a movable armature positioned at the high-expansion side of the bimetallic element and pivotally supported adjacent one end on one end of the U-shaped core member, said armature having its other end movable toward the other end of the U-shaped core member and having a portion which engages the bimetallic element to bend it in the same direction as it bends when heated and thereby causes the actuating portion rigid with the bimetallic element to effect release of said releasable means, and said bimetallic element being free of said armature to continue moving when heated after the movable end of the armature has engaged the end of the U-shaped core member.

10. In a circuit breaker, relatively movable contacts, releasable means for effecting automatic opening of said contacts, a thermally responsive member electrically connected in series with said contacts and heated in response to the current of the circuit of the breaker, said thermally responsive member flexing when heated a predetermined amount in a direction to efiect release of said releasable means, and electromagnetic mean comprising a U-shaped core member energized by the flow of current through the breaker, an armature movable to effect release of said releasable means, said armature being pivotally mounted at one end adjacent the end of one leg of the U of the core member and havin its other end movable toward the end of the other leg of the U, said pivotal mounting including a leaf spring secured at one end adjacent one side of the leg of the U and extending around the pivot of the armature and having its other end fastened to the armature and biasing the movable end of the armature away from the core member.

11. In a circuit breaker, relatively movable contacts, releasable means for effecting automatic opening of said contacts, a thermally responsive member electrically connected in series with said contacts and heated in response to the current of the circuit of the breaker, said thermally responsive member flexing when heated a predetermined amount in a direction to efiect release of said releasable means, and electromagnetic means comprising a U-shaped core member embracing said thermally responsive member, said thermally responsive member acting as an energizing means for said core member, a movable armature pivotally supported on one leg of said U-shaped core member, said armature being operable by said core member in response to overload currents of predetermined value to engage and deflect said thermally responsive member to effect release of said releasable means, and said pivotal support for the armature including a leaf spring secured at one end adjacent one side of the U-shaped core member and extending around the pivot of the armature and having its other end fastened to the armature and biasing one end of the armature away from the core member.

12. In a circuit breaker, relatively movable contacts, a releasable member for eifecting automatic opening of said contacts, a bimetallic element mounted at one end on a conducting strip and having its other end electrically connected to one of said contacts so as to be heated in response to the current through the breaker, said bimetallic member flexing when heated a predetermined amount in a direction to effect release of said releasable member, an electromagnetic trip device including a core member secured to said conducting strip between one side of said bimetallic element and the conducting strip so as to be energized by the current flow, a movable armature on the other side of the bimetallic element, an insulating member between the movable armature and the bimetallic element, and said armature being moved magnetically toward the core member in response to overload currents of predetermined value to deflect said thermal element through said insulating member and matic opening of said contacts, a bimetallic element mounted at one end on a conducting strip and having its other end electrically connected to one of said contacts so as to be heated in response to the current through the breaker, said bimetallic member flexing when heated a predetermined amount in a direction to effect release of said releasable member, an electromagnetic trip device including a core member secured to said conducting strip between one side of said bimetallic element and the conducting strip so as to be energized by the current flow, a movable armature on the other side of the bimetallic element, said armature being pivoted at one end adjacent one end of the core member and having an air gap between its other end and the other end of the core member, an insulating member between the movable armature and the bimetallic element, said armature being moved magnetically toward the core member to reduce said air gap in response to overload currents of predetermined value to deflect said thermal element through said insulating member and effect release of said releasable member, and said bimetallic element being free to move without restraint from said armature after said air gap is closed.

14. In a circuit breaker, relatively movable contacts, a releasable member for efiecting automatic opening of said contacts, a bimetallic element mounted at one end on a conducting strip and having its other end electrically connected to one of said contacts so as to be heated in response to the current through the breaker, said bimetallic member flexing when heated a predetermined amount in a direction to effect release of said releasable member, an electromagnetic trip device including a core member secured to said conducting strip between one side of said bimetallic element and the conducting strip so as to be energized by the current flow, a movable armature on the other side of the bimetallic element, said armature'being moved magnetically toward the core member in response to overload currents of predetermined value to deflect said thermal element and effect release of said releasable member, and said bimetallic element being free to move when heated without restraint from said armature after the armature has engaged the core member.

HARLAN S. GANO. GERALD J. FREESE.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,300,884 Gano Nov. 3, 1942 2,312,169 Jackson Feb. 23, 1943 2,419,125 Dorfman et al. Apr. 15. 1947 

